1. Technical Field
The present invention is directed to a method and apparatus for measuring thermal and electrical properties of thermoelectric materials.
2. Description of Related Art
One of the major difficulties in developing novel thin film thermoelectric materials lies in obtaining consistent and accurate measurement of their thermal and electrical properties. Traditional methods cannot be easily extended to microscopic characterization because of increased electrical and thermal parasitic losses associated with the probes used to perform the measurements. Additionally, the poor structural stability of some of the novel materials being investigated makes using traditional probe methods unworkable.
For example, in the case of measurements using a probe, such as the xe2x80x9cZT-meter,xe2x80x9d the time-scales of the transients become short and introduce errors in electrical measurements. Thus it would be beneficial to have an apparatus and method capable of performing measurements of thermal and electrical properties of thermoelectric materials in which the problems of the known methods with regard to thermal parasitic losses and structural stability of the thermoelectric materials, is overcome.
The present invention provides a method and apparatus for measuring and characterizing microscopic thermoelectric material samples using scanning atomic force microscopes. The methods rely on concurrent thermal and electrical measurements using scanning thermal probes, and extends the applicability of scanning thermal microscopes (SThMs) to the characterization of thermoelectric materials.
The probe of the present invention makes use of two temperature sensors, such as two thermocouples, to measure voltages at the tip and base of a cone tip of the probe. From these voltages, and from a voltage measured across the sample material, the Seebeck coefficient, thermal conductivity and resistance of the sample material can be accurately determined.
These thermoelectric properties may then be used in many different applications. For example, the thermoelectric properties may be used for characterization of scaled silicon devices wherein accurate spatial variation of Seebeck coefficient yields an exact dopant profiling with the silicon devices. Other features and advantages of the present invention will be described in or will become apparent to those of ordinary skill in the art in view of the following description of the preferred embodiment.